I wanted to point out a difference in the WRX and STi lateral links. As you can see above the STi ones have a single tab while the WRX ones have two for the different style endlinks.
You can see the difference in these pictures
The WRX ones appear to have a more substantial three sided attachment point for the endlink.
Not sure but this seems like it may only be an issue for the STi lateral links but conclusions should be held until TiC and MSI inspect the OP's broken parts.
These were purchased earlier this year so they are much newer than the ones in question.